Process for manufacturing a microelectromechanical interaction system for a storage medium

ABSTRACT

A process for manufacturing an interaction system of a microelectromechanical type for a storage medium, the interaction system provided with a supporting element and an interaction element carried by the supporting element, envisages the steps of: providing a wafer of semiconductor material having a substrate with a first type of conductivity and a top surface; forming a first interaction region having a second type of conductivity, opposite to the first type of conductivity, in a surface portion of the substrate in the proximity of the top surface; and carrying out an electrochemical etch of the substrate starting from the top surface, the etching being selective with respect to the second type of conductivity, so as to remove the surface portion of the substrate and separate the first interaction region from the substrate, thus forming the supporting element.

BACKGROUND

1. Technical Field

The present invention relates to a process for manufacturing amicroelectromechanical interaction system for a storage medium, inparticular for so-called “probe storage” applications, to which thefollowing treatment will make explicit reference, without this implyingany loss of generality.

2. Description of the Related Art

As is known, in the last few years alternative storage systems have beenproposed to overcome the limitations of traditional storage systemsbased on magnetism, such as, for example, hard disks. Amongst thesesystems, of particular importance are the so-called “probe storage”(also referred to as “atomic-level storage” or “atomic storage”)systems, which enable high data-storage capacities to be obtained insmall dimensions, with low manufacturing costs.

In brief (FIG. 1), a probe-storage device 1 comprises a two-dimensionalarray of interaction systems (or probes) 2, fixed to a common substrate3, for example made of silicon, in which a control electronics isprovided, for example using CMOS technology. The array is arranged abovea storage medium 4, typically not patterned, and is mobile relative tothe storage medium, generally in a first direction x and in a seconddirection y, which are mutually orthogonal, by the action of amicromotor associated therewith. Each interaction system 2 comprises: asupporting element 5 made of semiconductor material, in particularsilicon (generally known as “cantilever” or “cantilever beam”),suspended in cantilever fashion above the storage medium 4, and moveablein a third direction z, orthogonal to the first and second directions x,y so as to approach the storage medium 4; and an interaction element 6(also defined as “sensor” or “contact element”), carried by thesupporting element 5 at a free end thereof, and facing the storagemedium 4. In particular, by the term “interaction” is meant anyoperation of reading, writing or erasure of a single bit (or a number ofbits) of information, which implies an exchange of signals between theinteraction system 2 and the storage medium 4. Via the respectiveinteraction element 6, having nanometric dimensions, each interactionsystem 2 is able to interact locally at an atomic level with a portionof the storage medium 4, for writing, reading, or erasing bits ofinformation.

The physical characteristics (hardness, roughness, etc.), morphologicalcharacteristics (dimensions, shape, etc.) and electrical characteristics(resistivity, conductivity, etc.) of the interaction element 6 arestrictly correlated to the material of the storage medium 4 with whichit is associated (polymeric, ferroelectric, phase-change, etc.), and tothe interaction mechanisms for reading/writing/erasing data (thermal,piezoresistive, charge-transfer, etc.).

For example, storage systems of the probe-storage type have beendesigned, in which the interaction mechanisms involve thermal and/orpiezoresistive processes. In these systems, the interaction element 6has a sharpened shape, enabling the formation of “bits” with nanometricdimensions so as to increase storage density. In a known way, duringoperations of writing of data, the interaction element 6 is heated viaappropriate heating elements (for example, of a resistive type)integrated in the interaction system 2, and is pushed into contact withthe storage medium 4, for formation of single bits (the presence orabsence of a bit encoding in a binary way the data to be stored).Reading operations are based on resistance variations occurring in theinteraction system 2 as a function of temperature, or as a result of thepiezoresistive effect due to mechanical deformations, when theinteraction system is moved above the storage medium.

The processes for manufacturing probe-storage devices envisage in aknown way formation of the array of interaction systems 2 starting froman SOI (Silicon-On-Insulator) wafer, via micromachining techniques thatenvisage release of the various supporting elements 5 from an epitaxiallayer of the SOI wafer, via appropriate chemical etching of anunderlying oxide layer and if necessary of a bulk layer of the wafer.The interaction elements 6 are typically made prior to the step ofrelease of the corresponding supporting elements 5. The array ofinteraction systems 2 is then coupled to a CMOS wafer (substrate 3)integrating the associated interface/control electronics by means of“chip-to-wafer” or “wafer-to-wafer” bonding techniques.

Known manufacturing processes have a number of problems, amongst which:high costs, mainly due to the use of composite SOI wafers; the need toresort to wafer-to-wafer bonding techniques to couple the interactionsystems to the corresponding interface/control electronics; and theincompatibility with the so-called “CMOS back-end” (i.e. the formationof the MEMS structures after carrying out of the CMOS processes, in asame wafer of semiconductor material) due to thermal budget issues ofthe associated micromachining steps, and to recipe uniformity issues ofsilicon chemical etching. Furthermore, the steps of formation of theinteraction elements 6 and release of the supporting elements 5 pose aseries of problems of process integration, in particular for ensuring anadequate protection of the interaction elements 6 already formed, inprocess steps subsequent to their formation.

Up to now, fully satisfactory processes for manufacturing interactionsystems for probe-storage devices have not been proposed.

BRIEF SUMMARY

One embodiment of the present invention is a manufacturing process thatenables the aforesaid problems and disadvantages to be overcome.

According to the present invention, a process for manufacturing amicroelectromechanical interaction system for a storage medium isconsequently provided as defined in claim 1.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a better understanding of the present invention, there now follows adescription of some preferred embodiments thereof, provided purely byway of non-limiting example and with reference to the attached drawings,wherein:

FIG. 1 is a schematic perspective representation, partially in cutawayview, of a probe-storage device;

FIGS. 2a-9a are top plan views of a wafer of semiconductor material insuccessive steps of a process for manufacturing a microelectromechanicalinteraction system according to one embodiment of the present invention;

FIGS. 2b-9b are cross-sectional views of the wafer of semiconductormaterial taken along the lines II-II—IX-IX of FIGS. 2a -9 a; and

FIGS. 10-11 are cross-sectional views similar to that of FIG. 9b ,regarding variants of the microelectromechanical interaction system.

DETAILED DESCRIPTION

In detail, the process for manufacturing an interaction system 2 for astorage medium 4 according to one embodiment envisages first (FIGS.2a-2b ) the provision of a wafer of semiconductor material, inparticular monocrystalline silicon, comprising a monolithic substrate ofa standard (non-composite) type, designated by 10, having a conductivityof a P type, and a top surface 10 a. The process proceeds with theexecution of an implant with N-type conductivity through an appropriateresist mask (not illustrated), for formation, within a surface portionof the substrate 10 at the top surface 10 a, of a doped region 11 havingN-type conductivity. In particular, the doped region 11 comprises afirst interaction region 11 a, the shape of which, after appropriatediffusion of the implant, corresponds to a desired shape for thesupporting element 5 of the interaction system 2, and a body region 11b, from which the first interaction region 11 a extends. For example,the first interaction region 11 a comprises a first arm 12 and a secondarm 13, extending in a first direction x and separated by the substrate10 in a second direction y transverse to the first direction x, and aconnection portion 14, connecting together the ends of the first andsecond arms not connected to the body region 11 b (and extendingtransverse to an extension direction of the arms, in the seconddirection y). As will be clarified in what follows, the depth of theimplant and the following diffusion determine a thickness of thesupporting element 5, which is, for example, of the order of micron.

Next (FIGS. 3a-3b ) an implant with a P-type conductivity is carried outthrough a further mask of appropriate shape and dimension (notillustrated), for formation, within a surface portion of the dopedregion 11, of a resistor region 15, having a P-type doping and designedto form a heating resistor buried within the supporting element 5. Inparticular, the resistor region 15 extends within the first interactionregion 11 a, having the shape thereof (hence having respective first andsecond arms 15 a, 15 b and a respective connection portion 15 c), andhas within the body region 11 b two electrical connection portions 15 d,15 e connected to the respective first and second arms 15 a, 15 b.

A first epitaxial growth of an N type is then carried out (FIGS. 4a-4b), which involves the entire top surface 10 a of the substrate 10, forformation of a first epitaxial layer 16 on the substrate 10. Inparticular, the first epitaxial layer 16 closes the resistor region 15at the top, in this way forming a buried resistor.

A first implant mask 17 is then formed (FIGS. 5a-5b ) on the firstepitaxial layer 16, arranged above the entire doped region 11. Throughthe first implant mask 17 a P-type implant is carried out within theuncovered portion of the first epitaxial layer 16; the implant iscalibrated so as to involve the entire thickness in order to reverse theconductivity thereof and thus form a sacrificial region 18, with aP-type doping, which joins to the substrate 10. The doped sacrificialregion 18 defines and delimits a cover region 16 a, constituted by theremaining portion of the first epitaxial layer 16 and set on the dopedregion 11.

Next (FIGS. 6a-6b ), a new epitaxial growth of an N type is carried out,which involves the entire surface of the wafer, for formation of asecond epitaxial layer 19 on the cover region 16 a and the sacrificialregion 18. As will be clarified in what follows, the thickness of thesecond epitaxial layer 19 determines a thickness (or height) of theinteraction element 6 of the interaction system 2; for example, thisthickness is comprised between 300 and 700 nm.

Next (FIGS. 7a-7b ), a second implant mask 20 is formed above the secondepitaxial layer 19, set in particular above a central area of theconnection portion 14 of the first interaction region 11 a, and aboveperipheral portions (i.e., portions arranged at sides not in contactwith the first interaction region 11 a) of the body region 11 b. Thesecond implant mask 20 has non-submicrometric smaller dimensions, forexample in the region of 1-2 μm, and a lay-out with a geometry that canvary in relation to a desired final shape of the interaction element 6.Typically, for an interaction element with a sharpened conical shape,the second implant mask has a circular lay-out above the connectionportion 14.

Through the second implant mask 20 (FIGS. 8a-8b ), a P-type implantationis then carried out within the second epitaxial layer 19 (calibrated sothat the depth of implantation after diffusion equals the thickness ofthe same epitaxial layer), followed by an appropriate lateral diffusionof the introduced dopants. The implantation leads to the reversal of theconductivity of the uncovered portion of the second epitaxial layer 19,throughout its thickness, forming a P-type doped region that joins up tothe sacrificial region 18 (from which henceforth it will no longer bedistinguished) and to the substrate 10. The sacrificial region 18, dueto the process of lateral diffusion, extends in part underneath thesecond implant mask 20 (the extension of the fronts of lateral diffusionunderneath the mask, decreasing, in a known way, as the level ofpenetration increases within the second epitaxial layer 19). In thisway, above the aforesaid central area of the connection portion 14, asecond interaction region 22 is defined, designed to form theinteraction element 6 and having a sharpened shape. Clearly, the shapeand the resulting size of the second interaction region 22 are dependenton the shape of the second implant mask 20 and on the implant parameters(in terms of energy and dose), and on the aforesaid lateral diffusion.In any case, the diffusion enables a sharpened structure to be obtainedwith sub-lithographic dimensions (where by “sub-lithographic dimension”is meant herein a dimension smaller than a minimum dimension obtainablewith a lithographic technique; for example, a sub-lithographic dimensionis smaller than 50 nm, in particular smaller than or equal to 20 nm).For example, the aforesaid fronts of lateral diffusion can meetunderneath the second implant mask 20, and the second interaction region22 can consequently have a conical shape with hollowed side walls,having a base with extension that is a function of the dimensions of thesecond implant mask 20, and a tip end having sub-lithographic dimension.The internal angle defined by the tip end, designated by α, is forexample comprised between 30° and 70°.

Next (FIGS. 9a-9b ), according to one embodiment, an electrochemical wetetching is carried out in the dark (i.e., without lighting sources) ofthe P-type semiconductor material of the wafer, in a highly selectiveway with respect to the N-type semiconductor material. In detail, theelectrochemical etch involves the sacrificial region 18 and anunderlying surface portion of the substrate 10 (which is contiguous tothe sacrificial region), and is calibrated so as to involve a thicknessof material greater than the sum of the thicknesses of the first andsecond epitaxial layers 16, 19 (equal to the thickness of thesacrificial region 18) and of the doped region 11, so as to involve alsoa portion of the substrate 10 underlying the first interaction region 11a of the doped region. Accordingly, definition of the interactionelement 6 (constituted by the second interaction region 22 freed fromthe sacrificial doped region 18), and release from the substrate 10 ofthe supporting element 5 of the interaction system 2 are simultaneouslyobtained; the supporting element 5 is thus suspended in cantileverfashion above the substrate 10 (in other words, it is separated at thebottom from the substrate) and is consequently actuatable in a thirddirection z, transverse to the plane xy. The interaction system 2 is atthis point defined, and comprises the supporting element 5 (constitutedby the first interaction region 11 a, integrating the resistor region15, and by the cover region 16 a) and the interaction element 6(constituted by the second interaction region 22). Evidently, the sameelectrochemical etch does not cause, instead, separation from thesubstrate 10 of the body region 11 b of the doped region 11, given thelarger dimensions of the body region in the plane xy.

In greater detail, the electrochemical etch is performed with a solutioncomprising: an appropriate percentage of hydrofluoric acid HF, rangingbetween 1 vol % and 25 vol %, preferably between 1 vol % and 5 vol %,even more preferably equal to 2.5 vol %; possible additives(surfactants, alcohol, etc.) in order to improve etching uniformity; andwater (H₂O), in the remaining part, for example in a percentage of 95vol %.

Furthermore, etching is carried out under anodization conditions (so asto cause dissolution, activated by holes, of the P-type silicon), andwith a current density J>J_(ps) and with a voltage V>V_(ps) (whereJ_(ps) and V_(ps) are, in a known way, values corresponding to anelectropolishing condition). For this purpose, an anodization voltage isapplied between the front and the back of the wafer through a conductivepath of a P type defined by the substrate 10 and by the sacrificialregion 18. The etching rate depends on the concentration of HF insolution and, once this is fixed, on the doping concentration of theP-type semiconductor material.

Afterwards, in a per-se known manner, the wafer of semiconductormaterial in which the interaction systems 2 have been formed, arrangedas an array (it is evident that the process described enablessimultaneous definition of a plurality of interaction systems 2 alignedin rows and columns), is coupled to a storage medium 4 (not illustratedherein) so as to be suspended above the same storage medium.

The advantages of the manufacturing process emerge clearly from theforegoing description.

In any case, it is emphasized that the use of monolithic standardsubstrates of semiconductor material, and not of SOI compositesubstrates, enables a reduction of the manufacturing costs. Inparticular, the electrochemical etch enables release of the supportingelement 5 from the substrate 10, removing a sacrificial surface portionof the same substrate.

It is possible to obtain a good control of the uniformity of thethickness of the supporting element 5, given that it is defined by meansof steps of epitaxial growth and implantation and diffusion of anN-doped region, and not via a chemical etching step, and of theuniformity of the thickness (or height) and of the sharpened shape ofthe interaction element 6, given that it is defined by means of steps ofimplantation and lateral diffusion, and once again not via a chemicaletching step. In particular, for the purposes of the applicationdescribed, it is extremely advantageous to obtain a good repeatabilityof the critical dimensions of the interaction element 6, withoutresorting to techniques of sub-micrometric lithography.

Given that the supporting element 5 and the interaction element 6 aredefined simultaneously in a single final (non-lithographic) step of themanufacturing process, problems of process integration do not arise,which are indeed associated with the need of protecting the tip duringprocess steps subsequent to its formation, and in particular during thestep of release of the supporting element 5.

The described process is also fully compatible with the back-end CMOStechnology, and an appropriate CMOS electronics can be provided withinthe same substrate 10, from which the microelectromechanical structuresare obtained. For example, as illustrated schematically in FIG. 9b , aCMOS electronics 25 for the interaction system 2 can be provided in aperipheral surface region of the body region 11 b, in a step prior tothe manufacturing of the microelectromechanical interaction system (therelease of the supporting element and the definition of the interactionelement being the final step of the manufacturing process). Masking,implantation and diffusion steps, common to the CMOS manufacturingprocess, can be used. In this way, it is also possible to avoid thecostly steps of wafer-to-wafer bonding characterizing the known art.

The portions of the second implant mask 20 set on the peripheralportions of the body region 11 b, in addition to separating adjacentinteraction systems 2 from one another, protect underlying regions thatmust not be etched and/or damaged during subsequent electrochemicaletching, in particular CMOS electronic circuits that might present inthe same substrate.

Finally, it is clear that modifications and variations can be made towhat is described and illustrated herein, without thereby departing fromthe scope of the present invention, as defined in the annexed claims.

The steps involving formation of the buried heating resistor can beomitted, in the case where interaction with the storage medium 4 doesnot require local heating (for example because it is based entirely onpiezoresistive processes). In particular, the steps of formation of theresistor region 15 (FIGS. 3a-3b ), formation of the first epitaxiallayer 16 (FIGS. 4a-4b ), and implantation of a P type through the firstimplant mask 17 (FIGS. 5a-5b ) could be omitted; the subsequentimplantation of a P type through the second implant mask 20 (FIGS. 8a-8b), and the corresponding lateral diffusion, are in this case inthemselves able both to define the tip and to create a path of a P typetowards the substrate 10 for the subsequent electrochemical etching.

Furthermore, the electrochemical etch might be calibrated in such a wayas to remove the substrate 10 underneath the interaction region 11 a,throughout its thickness.

According to a variant of the present invention, the process steps areexploited for formation of a further interaction element 6′,simultaneously with formation of the interaction element 6 describedpreviously. For example, the presence of two interaction elements 6, 6′can be advantageous, in a per-se known manner that is not described indetail, to carry out combined operations of reading and rewriting of thedata previously erased during the reading step, in the case where thestorage medium 4 comprises ferroelectric material. It will in this casebe sufficient to modify the second implant mask 20 to obtain theinteraction system illustrated in FIG. 10, where two interactionelements 6, 6′ are aligned in the second direction y, transverse to thedirection of extension of the first and second arms 12, 13. In a similarway, the process described is suited to formation of a number ofinteraction elements greater than two by appropriately modifying theaforesaid implant mask; the interaction elements thus obtained can alsonot be aligned with one another, and set according to a desiredconfiguration.

Furthermore, the interaction element 6 could have a shape different fromthe one illustrated, for example, it could have a rectangular,elliptical or generically polygonal base. As illustrated in FIG. 11, inthe case where the fronts of lateral diffusion of the implantation donot meet underneath the second implant mask 20 (due to a modification ofthe dimensions of the second implant mask 20, or to a modification ofthe implantation parameters), the interaction element 6 has an upper endwith a flat surface (with a width depending on the aforesaid dimensionsand the aforesaid parameters).

In addition, the process described can be adapted to enable formation ofinteraction elements 6 made of non-semiconductor material, for examplemetal. In this case, the interaction element 6 can be obtained prior torelease via electrochemical etching of the supporting element 5 from thesubstrate 10.

The interaction system 2 can be associated to storage media of a widerange of materials, for example ferroelectric, polymeric or phase-changematerials, and used in any application in which a sub-lithographicsmaller dimension for interaction with a storage medium is desired.

Finally, the process described, envisaging release of regions withN-type doping from a P-type substrate via selective electrochemicaletching, could be used for formation of further MEMS structures, forexample buried cavities for pressure sensors, or buried channels for“Lab-on-Chip” applications.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet, areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

The invention claimed is:
 1. A process, comprising: manufacturing amicroelectromechanical interaction system for a storage medium, saidinteraction system including a supporting element and an interactionelement carried by said supporting element, the manufacturing including:forming, in a semiconductor wafer having a substrate with a first typeof conductivity and a top surface, a first interaction region having asecond type of conductivity, opposite to said first type ofconductivity, in a surface portion of said substrate in proximity ofsaid top surface; and electrochemically etching said substrate startingfrom said top surface, selective with respect to said second type ofconductivity, the electrochemically etching including removing saidsurface portion of said substrate and separating said first interactionregion from said substrate, thus forming said supporting element.
 2. Theprocess according to claim 1, wherein said first conductivity is of a Ptype and said second conductivity is of an N type; saidelectrochemically etching being carried out in a dark condition with anaqueous solution of HF.
 3. The process according to claim 2, whereinsaid solution comprises a percentage of hydrofluoric acid HF comprisedbetween 1 vol % and 25 vol %.
 4. The process according to claim 1,wherein after said electrochemically etching, said supporting element issuspended in cantilever fashion above said substrate, and saidinteraction element has a sharpened shape facing in a direction oppositeto said substrate.
 5. The process according to claim 1, comprising,prior to the electrochemically etching, forming a path with said firsttype of conductivity between said top surface and an opposite bottomsurface of said semiconductor wafer.
 6. The process according to claim1, wherein said first interaction region comprises first and second armsextending in a first direction, and a connection portion extending in asecond direction, transverse to said first direction, and joining saidfirst and second arms at first ends of the first and second arms; saidfirst and second arms being separated in said second direction by saidsubstrate.
 7. The process according to claim 6, further comprising,simultaneously to forming the first interaction region, forming, in afurther surface portion of said substrate, a body region, having saidsecond type of conductivity and joined to said first interaction region,said first and second arms extending from said body region in said firstdirection, and joined at second ends of the first and second arms tosaid body region.
 8. The process according to claim 1, wherein formingthe first interaction region comprises introducing dopant species ofsaid second type of conductivity within said substrate, and defining athickness of said supporting element by controlling a depth ofintroduction of said dopant species.
 9. The process according to claim1, further comprising forming, above said top surface and above aspecific portion of said first interaction region, a second interactionregion having said second type of conductivity, said second interactionregion being surrounded by a sacrificial region, having said first typeof conductivity and having a bottom joined to said substrate; whereinsaid electrochemically etching further comprises defining saidinteraction element on top of said supporting element by removing saidsacrificial region, in a way substantially simultaneous to separatingsaid first interaction region from said substrate.
 10. The processaccording to claim 9, wherein forming the second interaction regioncomprises: forming an epitaxial structural layer on said top surface;forming a mask region on said structural layer, above said specificportion of said first interaction region; and introducing dopant speciesof said first type of conductivity within said structural layer throughsaid mask region for reversing a conductivity of said structural layer,thus defining said second interaction region underneath said mask regionand creating a path having said first type of conductivity towards saidsubstrate.
 11. The process according to claim 10, wherein said firstinteraction region comprises first and second arms extending in a firstdirection, and a connection portion extending in a second direction,transverse to said first direction, and joining said first and secondarms at first ends of the first and second arms; said first and secondarms being separated in said second direction by said substrate, whereinsaid specific portion of said first interaction region is set centrallyabove said connection portion.
 12. The process according to claim 10wherein introducing dopant species of said first type of conductivitycomprises implanting, and subsequently diffusing underneath said maskregion, said dopant species; and defining a desired dimension and shapeof said interaction element by controlling parameters of said implantingand of said diffusing, and/or dimensions of said mask region.
 13. Theprocess according to claim 12 wherein said defining is such that saidinteraction element has nanometric smaller dimensions, and a sharpenedshape with a tip end facing away from said top surface of saidsubstrate.
 14. The process according to claim 12 wherein said definingis such that fronts of said diffusing meet underneath said mask region,so that said interaction element has a conical shape with hollowedwalls.
 15. The process according to claim 9, further comprising: forminga resistor region, having said first type of conductivity, within saidfirst interaction region; and prior to said forming the secondinteraction region, forming a cover region, having said second type ofconductivity, on said first interaction region, the covering regionburying the resistor region within said first interaction region. 16.The process according to claim 15 wherein said forming the cover regioncomprises: forming an epitaxial cover layer on top of said substrate;and reversing a conductivity of said cover layer except at the top ofsaid first interaction region, thus forming said cover region on saidfirst interaction region, and a sacrificial region elsewhere, designedto create a path having said first type of conductivity towards saidsubstrate.
 17. The process according to claim 1 wherein said substrateis monolithic, and said semiconductor material is monocrystallinesilicon.
 18. A process for manufacturing a probe-storage device,comprising: forming a storage medium; forming an interaction system witha supporting element and an interaction element carried by saidsupporting element, forming the interaction system including: forming,in a semiconductor wafer having a substrate with a first type ofconductivity and a top surface, a first interaction region having asecond type of conductivity, opposite to said first type ofconductivity, in a surface portion of said substrate in proximity ofsaid top surface; and electrochemically etching said substrate startingfrom said top surface, selective with respect to said second type ofconductivity, the electrochemically etching removing said surfaceportion of said substrate and separating said first interaction regionfrom said substrate, thus forming said supporting element; and couplingsaid interaction system to the storage medium in such a way that saidsupporting element is suspended in cantilever fashion above said storagemedium and said interaction element faces said storage medium.
 19. Theprocess according to claim 18, further comprising, at least in partprior to forming said interaction system, forming correspondingelectronics within said substrate, via CMOS processes.
 20. The processaccording to claim 19 wherein said electronics are made beforeelectrochemically etching said substrate.
 21. The process according toclaim 18, comprising forming an array of said interaction systems insaid surface portion of said substrate, arranged in rows and columns;said electrochemically etching separating simultaneously the supportingelements of said interaction systems from said substrate.
 22. A methodof making a microelectromechanical interaction system, comprising:forming a monocrystalline semiconductor first supporting elementextending in cantilever fashion from a monocrystalline semiconductorsubstrate, the substrate and first supporting element being parts of thesame monolithic crystal; forming a CMOS control circuit within saidsubstrate; and forming a first interaction element carried by said firstsupporting element.
 23. The method of claim 22 wherein the substrate hasa first conductivity type and the supporting element and interactionelement have a second conductivity type opposite to the firstconductivity type.
 24. The method of claim 23, further comprisingforming a resistor of the first conductivity type within the supportingelement.